Although depression care management improves outcomes, its widespread uptake is hindered by limitations in infrastructure, reimbursement, and interventionist time. As a result, care managers are often unable to provide the time intensive support that many depressed patients need in order to achieve optimal outcomes. While this service gap can be partly offset by support from an in-home caregiver (ICG), ICGs lack formal tools to effectively monitor patients' clinical needs and support their self-management. ICGs are also at risk for caregiver burnout due to competing demands and social isolation. Finally, many patients have no ICG. We propose to address these problems with a practical intervention that uses low cost technologies to activate depressed patients' existing social networks for self-management support, without requiring patients to use a computer. The intervention links patients with a CarePartner (CP), i.e., a non-household family member or close friend who is willing to support the patient in coordination with the clinician and any existing ICG. Through weekly automated telemonitoring, patients report their mood and self-management status, and receive tailored guidance on self-management. The CP receives a corresponding update along with guidance on how to best support the patient's self-management efforts, and the primary care team is notified about clinically urgent situations. Our pilot work demonstrates the intervention's feasibility and potential effectiveness, such that patients consistently engaged in telemonitoring, CP and clinician reports were successfully issued, and depressive symptoms reduced significantly. We now plan to rigorously evaluate the intervention's efficacy among depressed primary care patients from clinics serving low-income and underinsured patients, whom the intervention was especially designed to benefit. Specific Aim 1 is to conduct an RCT to compare the effectiveness of one year of telemonitoring-supported CP for depression versus usual care (control) on depression severity. Specific Aim 2 is to examine key secondary outcomes (response and remission, impairment, well-being, caregiving burden, healthcare costs) and potential moderators. Specific Aim 3 is to use a mixed-methods approach to enrich our interpretation of the statistical associations, and to discover strategies to enhance the intervention's acceptability, effectiveness, and sustainability. If the intervention proves effectie without increasing clinician burden or marginal costs, then its subsequent implementation could yield major public health benefits, especially in medically underserved populations. Societal benefit may also occur through the promotion of helping behavior and social ties. Follow-up research could implement the intervention, and extend its focus to specific depression subtypes as well as other chronic psychiatric disorders. In this resubmitted proposal, we respond to Reviewers' feedback by adding specialized experts to our team, strengthening our participant protections, and providing additional methodological details.